合成路线1

. 4-Hydroxycinnamic acid (XV) was acetylated with Ac2O in pyridine, and the resultant 4-acetoxycinnamic acid (XVI) was converted to the cinnamyl alcohol (XVIII) via conversion to the mixed anhydride (XVII) and subsequent reduction with NaBH4. Sharpless asymmetric epoxidation of (XVIII) furnished the chiral epoxide alcohol (XIX). After oxidation of alcohol (XIX) to the glycidic acid (XX) by means of RuO2/NaIO4, treatment with dimethyl sulfate and Et3N gave rise to the corresponding methyl ester (XXI). Epoxide opening in (XXI) with HCl and pyridine hydrochloride produced chlorohydrin (XXII) as a mixture of the desired (2S,3R)-isomer and minor amounts of the corresponding 3-chloro epimer. Condensation of (XXII) with 2-nitrothiophenol (XXIII) provided, after recrystallization from EtOH, the pure (S,S)-thioether adduct (XXIV). The hydroxyl group of (XXIV) was then protected as the methoxymethyl ether (XXV) by means of methylal in the presence of P2O5